U.S. patent number 5,902,568 [Application Number 08/979,645] was granted by the patent office on 1999-05-11 for method for whitening teeth.
This patent grant is currently assigned to Chesebrough-Pond's USA Co., Division of Conopco, Inc.. Invention is credited to Stephen Roy Barrow, Christine Watson Ryles, David Robert Williams.
United States Patent |
5,902,568 |
Ryles , et al. |
May 11, 1999 |
Method for whitening teeth
Abstract
A method for whitening teeth is provided which involves applying
to the teeth a mixture of a peroxide and a bicarbonate salt.
Advantageously, the peroxide and bicarbonate salt are stored as
active ingredients in separate respective compositions of a
dispensing container. Preferably the dispensing container is a pump
in the form of an upper and lower body telescopically engageable
one with another, the upper body including at least two hollow and
separate parallel cylinders each containing one of the
compositions. These compositions may then be dispensed through
relative compression of the pistons within the cylinders.
Inventors: |
Ryles; Christine Watson
(Milford, CT), Barrow; Stephen Roy (Trumbull, CT),
Williams; David Robert (Monroe, CT) |
Assignee: |
Chesebrough-Pond's USA Co.,
Division of Conopco, Inc. (Greenwich, CT)
|
Family
ID: |
25130974 |
Appl.
No.: |
08/979,645 |
Filed: |
November 26, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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783972 |
Jan 15, 1997 |
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Current U.S.
Class: |
424/53; 424/49;
424/613; 424/717; 424/616 |
Current CPC
Class: |
A61K
8/19 (20130101); A61K 8/22 (20130101); A61Q
11/00 (20130101); A61K 2800/88 (20130101) |
Current International
Class: |
A61Q
11/00 (20060101); A61K 8/19 (20060101); A61K
8/22 (20060101); A61K 007/16 (); A61K 007/20 ();
A61K 033/40 () |
Field of
Search: |
;424/49-88 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 388 185 |
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Sep 1990 |
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EP |
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2 290 234 |
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Dec 1995 |
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GB |
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88/06879 |
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Sep 1988 |
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WO |
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95/09603 |
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Apr 1995 |
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WO |
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96/28133 |
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Sep 1996 |
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WO |
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97/11676 |
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Apr 1997 |
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WO |
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97/21419 |
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Jun 1997 |
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WO |
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Other References
Colgate Baking Soda & Peroxide Carton -1996..
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Primary Examiner: Rose; Shep K.
Attorney, Agent or Firm: Honig; Milton L.
Parent Case Text
This application is a continuation in part of application Ser. No.
08/783,972 filed Jan. 15, 1997, now abandoned.
Claims
What is claimed is:
1. A method for whitening teeth comprising:
(i) providing an oral composition which includes a first and second
composition each of which is stored separate from one another prior
to time of use, the first composition containing from 0.01 to 20%
of a peroxide by weight of the oral composition, and the second
composition containing from 0.05 to 60% of a bicarbonate salt by
weight of the oral composition, and the oral composition having a
pH from 9.0 to 12;
(ii) dispensing the first and second compositions onto a
toothbrush;
(iii) applying the first and second compositions from the
toothbrush to the teeth:
(iv) brushing the teeth thereby mixing first and second
compositions together; and
(v) repeating steps (ii) through (iv) on a plurality of days, the
teeth to be whitened being exposed to the oral composition for the
equivalent of 10 seconds to 5 minutes per day exposure until the
delta L values of the equivalent use time of combined peroxide and
bicarbonate compositions provide substantially greater whitening
effect than additive results of tooth whitening with either
peroxide or bicarbonate compositions used separately, as
represented by differences between colorimeter readings of tooth
base line versus values after exposure.
2. The method according to claim 1 wherein each of the first and
second compositions are semi-solids.
3. The method according to claim 1 wherein the peroxide is hydrogen
peroxide.
4. The method according to claim 3 wherein hydrogen peroxide is
present in an amount from 0.5 to 10% by weight of the oral
composition.
5. The method according to claim 1 wherein sodium bicarbonate is
present in an amount from 0.05 to 40%.
6. The method according to claim 1 wherein the oral composition is
dispensed from a dispensing container in pump form.
7. The method according to claim 6 wherein the dispensing container
has an upper and a lower body which are telescopically engageable
one with another, the upper body including at least two hollow and
separate parallel cylinders, the cylinders having a first generally
closed end and a second end telescopically and slidingly
accommodating at least two parallel pistons which conform to ride
sealingly along the interior walls of the cylinders so as to force
any flowable materials to flow toward the first end of the cylinder
upon relative compression of the cylinders and pistons, the
cylinders having outlet channels;
an outlet means in fluid communication with the outlet channels,
the outlet means including adjacent outlet openings unconnected to
each other and having means for causing the flowable materials to
flow toward each other at the outlet openings to form a banded,
unmixed stream;
the first and second compositions being the flowable materials and
stored in separate ones of the at least two hollow parallel
cylinders; and
the method further comprising the step of actuating the dispenser
container to dispense the unmixed stream.
8. The method according to claim 7 wherein the unmixed stream is
placed upon a toothbrush and applied to the teeth, and mixing is
performed in the mouth so as to whiten the teeth.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a method for whitening teeth which removes
stain and leaves surfaces brighter.
2. The Related Art
People to some extent are judged by their smile. It is little
wonder then that people are concerned with the appearance of their
teeth. Stained ugly surfaces detract from the warmth intended to be
conveyed by the smile. Stains arise from certain foods, tartar
buildup, side effects of medicine and most especially smoking.
Abrasives in dentifrices are a first line of defense in combatting
stains. Usually they deliver adequate but not superlative
performance. An additional drawback is that abrasives, especially
in higher concentrations, may damage enamel. Certain types of
stains like those arising from smoking are often not removed by
abrasive action alone.
Peroxides have been suggested as whitening agents. Unless employed
at relatively high levels and in the presence of a catalyst, the
peroxides are only modestly efficient in bleaching enamel.
Oral compositions with peroxide and baking soda (i.e. sodium
bicarbonate) have become commercially quite popular. The
combination of actives has been reported to promote healthy gums.
When in contact, peroxide and baking soda are reactive towards one
another. Therefore these ingredients must be maintained separately
until time of use. Dispensing packages have been developed which
physically isolate peroxide and baking soda by separating them into
different compartments. This approach has been described in a
series of patents to Schaeffer including U.S. Pat. No. 4,849,213,
U.S. Pat. No. 4,528,180 and U.S. Pat. No. 4,687,663. Products based
on this technology have been commercially sold in the United States
under the Mentadent.RTM. brand of Peroxide and Baking Soda
toothpastes. Mentadent.RTM. has been promoted for its gum care and
antitartar properties. Hitherto there had been no indication that
this product had any special effectiveness in whitening teeth.
Variants of the Mentadent.RTM. brand toothpaste ranged in pH from
about 7.5 to about 8.5 for a mixture of equal volume streams
peroxide and baking soda.
It is an object of the present invention to provide a method for
treating teeth to enhance their whiteness.
Another object of the present invention is to provide a method for
whitening teeth which achieves its affect more rapidly than other
previously known procedures.
Still another object of the present invention is to provide a
method for whitening teeth employing relatively low levels of
water-insoluble abrasives.
These and other objects of the present invention will become more
readily apparent from consideration of the following summary and
detailed discussion.
SUMMARY OF THE INVENTION
A method for whitening teeth is provided which includes:
(i) providing an oral composition which includes a first and second
composition each of which is stored separate from one another prior
to time of use, the first composition containing from 0.01 to 20%
of a peroxide by weight of the oral composition, and the second
composition containing from 0.05 to 60% of a bicarbonate salt by
weight of the oral composition, and the oral composition having a
pH from 9.0 to 12;
(ii) dispensing the first and second compositions onto a
toothbrush;
(iii) applying the first and second compositions from toothbrush to
the teeth;
(iv) brushing the teeth thereby mixing first and second
compositions together; and
(v) repeating steps (ii) through (iv) on a plurality of days.
A preferred method of storage and dispensing involves use of a dual
compartment dispensing container in the form of a pump. The
dispensing container preferably is structured with an upper and
lower body telescopically engageable one with another, the upper
body including at least two hollow and separate parallel cylinders
containing the respective first and second compositions.
BRIEF DESCRIPTION OF THE DRAWINGS
The above features, advantages and objects of the present invention
will more fully be appreciated through the following detailed
discussion, reference being made to the drawing consisting of a
single FIGURE which is an expanded view of a telescopically
arranged multi-cavity dispensing pump.
DETAILED DESCRIPTION
Now it has been discovered that teeth may be efficiently whitened
by applying thereto a mixture of hydrogen peroxide and sodium
bicarbonate. Furthermore it has been found that relatively high pH
substantially increases the whitening effect. In particular, it has
been found highly effective to employ a pH range from 9.0 to 12,
particularly from 9.5 to 10.5 for the total oral composition as
measured on a mixed equal volume of the peroxide and the
bicarbonate containing streams. Each of the peroxide and
bicarbonate actives are incorporated into compositions held
separate from one another until just prior to use. Particularly
useful is a storage and delivery system utilizing a dispensing pump
container having two separate compartments. When the compositions
are in the form of semisolids (i.e. a toothpaste), the dispensing
container is of the type shown in the Figure.
The dispensing container includes an upper body 2 and a lower body
4, the former telescopically engaging within the latter. Within the
lower body 4 are a pair of parallel piston rods 6 rigidly standing,
and preferably unitarily molded with the lower body. These rods may
be hollow or solid. While the depicted configuration is round, the
rods may be rectangular or of any other polygonal shape.
Upper body 2 includes a pair of separate parallel cylinders 8 each
having a first generally closed end 10 and a second end 12
telescopically and slidingly accommodating piston heads 14. These
heads conform to ride sealingly along interior walls of the
cylinders so as to force flowable materials to flow towards the
first end of the cylinder. The cylinder walls may be formed as part
of the upper body or may be formed as refill cartridges separate
and removable from the upper body. Activation of flow is
accomplished by hand pressure downward on the top of the upper body
which pressure forces the upper body to telescopically descend
within the lower body. Movement of the bodies causes pistons 6 to
press against each of the respective piston heads 14 moving them
upward along respective cylinders 8. Flowable material in each of
the cylinders is then forced through a pair of outlet channels 16.
Flowable toothpaste exits the outlet channels passing in unmixed
streams through an outlet nozzle having a septum 18 maintaining
respective toothpastes in unmixed relationship to outlet openings
20.
First and second semi-solid extrudable streams of dentifrice will
be stored in each of the respective cylinders 8. The first of the
streams will include a peroxide. The peroxide should be capable of
generating hydrogen peroxide such as sodium perborate, persilicate,
percarbonate, perphosphate, calcium peroxide, sodium peroxide and
hydrogen peroxide. Most preferred is an aqueous solution of
hydrogen peroxide or an adduct such as urea peroxide. Amounts of
the peroxide may range from 0.01 to 20%, preferably from 0.5 to
10%, optimally from 1 to 5% by weight of the total oral
composition.
The peroxide containing composition may either be a liquid, paste
or gel, preferably the latter. When a gel, water will be present in
amounts ranging from 5 to 70%, preferably from 10 to 55%, optimally
between 20 to 40% by weight of the first composition.
For anti-caries protection, a source of fluoride ion will normally
be present in one or both of the first and second compositions of
the total oral composition. Fluoride sources include sodium
fluoride, potassium fluoride, stannous fluoride, stannous
monofluorophosphate and sodium monofluorophosphate. These sources
should release anywhere from 25 to 3500 ppm of fluoride ion. The
anti-caries agent will be present in an amount from 0.05 to 3% by
weight, preferably from 0.2 to 0.6% by weight of the total oral
composition.
A variety of other ingredients normally present in dentifrices can
be selected for the peroxide and bicarbonate compositions of the
present invention. When the peroxide composition is intended as a
gel, it is usual to employ with the water a thickening agent that
is a cross-linked acrylic polymer. Alternatively and most
preferably, gels can be structured with a
polyoxyethylene-polyoxypropylene copolymer. Commercially,
copolymers are available from the BASF Corporation under the
trademark Pluronic F88, F99, F108 and F127. Most preferred is
Pluronic F127 (more commonly described by its CTFA name, Poloxamer
407) which has a molecular weight ranging from 10,000 to 15,000,
and containing 70% of the hydrophilic polyoxyethylene moiety.
Amounts of the copolymer can range anywhere from 18-25% by weight,
preferably between 19 and 24%, by weight of the peroxide containing
stream. Poloxamers are particularly suitable for this invention
because of their wide pH tolerance, high compatibility with
hydrogen peroxide and unique gel properties.
Advantageously, glycerol may also be present in the peroxide
composition in an amount from 15 to 60%, preferably in an amount
greater than 30% but less than 50%, optimally between 35 to 45% by
weight of the peroxide containing stream.
A low pH, preferably a pH no higher than 6, optimally less than
5.0, is maintained for peroxide gels. Acidification is best
accomplished through use of a phosphorus-based inorganic or organic
acid. Where Carbomer is used as a gel structurant, pH can be as
high as 7.5.
The second composition of the oral compositions of the invention
will be a bicarbonate-containing composition , preferably an opaque
paste. Advantageously, the bicarbonate will be the salt of an
alkali metal such as sodium or potassium. Normally, the bicarbonate
is included in the composition in an amount sufficient to provide a
neutral or basic pH when the total oral composition is contacted
with water. Bicarbonate optimally in combination with other
alkaline materials such as sodium carbonate can be present in
amounts to preferably achieve a pH of from 8.0 to 12, most
preferably 8.5 to 11, optimally 9.0 to 11 for the bicarbonate
containing stream i.e. the second composition. Typically, the
concentration will range from 0.05 to 60%, preferably from 1 to
40%, optimally between 3 and 30% by weight of the second
composition.
A humectant and water system will normally be included. Humectants
are usually polyols which, for example, may include glycerol,
sorbitol, propylene glycol, lactitol, xylitol, polypropylene
glycol, polyethylene glycol, hydrogenated corn syrup and mixtures
thereof. Generally the amount of humectant will range from 25 to
90%, preferably from 40 to 70% by weight of the first or second
semi-solid material. Particularly preferred is a liquid mixture of
3 to 30% water, 0 to 80% glycerol and/or 20 to 80% sorbitol.
A natural or synthetic thickening agent may be present in an amount
from 0.1 to 10%, preferably 0.5 to 5% by weight of the second
composition. Thickeners may include hydroxypropyl methylcellulose,
hydroxyethyl cellulose, sodium carboxymethyl cellulose, xanthan
gum, tragacanth gum, karaya gum, arabic gums, Irish moss, starch,
alginates and carrageenans.
Surfactants are normally also included in the compositions,
especially in the bicarbonate compositions of this invention. These
surfactants may be of the anionic, nonionic, cationic or amphoteric
type. Most preferred are sodium lauryl sulfate, sodium
dodecylbenzene sulfonate and sodium laurylsarcosinate. Surfactants
are usually present in an amount from 0.5 to 5% by weight of a
respective first or second composition.
Anti-tartar agents may also be included. Most suitable are
polyphosphate salts, especially tripolyphosphate and
pyrophosphates. Counterions for these phosphates may be the alkali
metal, alkaline earth metal, ammonium, C.sub.2 --C.sub.6
alkanolammonium and salt mixtures thereof. Representative of
polyphosphates are sodium tripolyphosphate, sodium
hexametaphosphate, potassium hydrogen phosphate, sodium hydrogen
phosphate, disodium pyrophosphate, dipotassium pyrophosphate,
tetrasodium pyrophosphate, tetrapotassium pyrophosphate and
mixtures of these salts. Amounts of the polyphosphate may range
from 0.5 to 20%, preferably from 1 to 8%, optimally from 1.2 to
4.5% by weight of the oral composition. As an alternative to
phosphates, zinc salts may be utilized as anti-tartar agents. Most
preferred is zinc citrate trihydrate. Amounts of the zinc salt may
range from 0.5 to 20%, preferably from 1 to 8%, optimally from 2 to
6% by weight of the oral composition.
An abrasive in addition to the bicarbonate will normally be
included in the second composition. Abrasives may be selected from
water-insoluble alkali or alkaline earth metal salts of carbonate,
aluminate and silicate. Especially preferred are silica, and
alumina. Amounts of the abrasive will range from 5 to 80%,
preferably from 10 to 30% by weight of the oral composition.
Sweetening agents such as saccharin, sodium cyclamate, aspartame,
sucrose and the like may be included at levels from 0.1 to 5% by
weight of the oral composition.
Other additives may also be incorporated into the oral compositions
including preservatives, silicones, other synthetic or natural
polymers such as Gantrez S-97, and anti-gingivitis active. Pigments
such as titanium dioxide may also be incorporated for their
opacifying effect at levels which may range from 0.01 to 1%,
preferably from 0.1 to 0.5%, optimally from 0.15 to 0.2% by weight
of the total oral composition. The amounts and particle size or
morphology of titanium dioxide should not interfere either to
enhance or detract from the whitening effect of the
peroxide/bicarbonate interaction.
In the method of the present invention, the first and second
compositions with respective peroxide and bicarbonate components
are dispensed in approximately equal volume onto a bristle head of
a toothbrush. The toothbrush head with the compositions is then
applied to the teeth where the first and second compositions are
mixed together during brushing action. A certain level of whitening
is achieved in the first application but the procedure is intended
for repeated use on a plurality of days. Each exposure on the teeth
should last anywhere from 10 seconds to 5 minutes, preferably from
30 seconds to 3 minutes, and optimally about 2 minutes per
brushing. Advantageously there are two brushings per day. Best
effectiveness is achieved when the number of days brushing are at
least 7, preferably 15 days and optimally at least 30 days.
The following examples will more fully illustrate the embodiments
of this invention. All parts, percentages and proportions referred
to herein and in the appended claims are by weight of the total
composition unless otherwise stated. Except in the examples, or
where otherwise explicitly indicated, all numbers in this
description indicating amounts of material or conditions are to be
understood as modified by the term "about".
EXAMPLE 1
Typical of whitening paste and gel compositions of the present
invention are those detailed under Tables I and II.
TABLE I ______________________________________ Bicarbonate Paste
Composition INGREDIENT WT. % ______________________________________
Polyol II (sorbitol and other sugars) 33.60 Syloid 63XX (abrasive
silica) 30.00 Sodium Bicarbonate 10.00 PEG 32 (polyethylene glycol)
5.00 Sylox 15x (thickening silica) 2.00 Flavor 1.00 Sodium Lauryl
Sulfate 2.98 SD Alcohol 38B 2.84 Cellulose Gum 0.80 Sodium
Saccharin 0.54 Menthol 0.50 Sodium Fluoride 0.44 Titanium Dioxide
0.30 Deionized Water Balance
______________________________________
TABLE II ______________________________________ Peroxide Gel
Composition COMPONENT WT. % ______________________________________
Glycerin 40.00 Pluronic F127 20.00 Hydrogen Peroxide (35% food
grade) 4.285 Zinc Citrate Trihydrate 4.00 FD&C Blue 0.005
Phosphoric Acid (85% w/w) 0.15 Deionized Water Balance
______________________________________
EXAMPLE 2
Another set of compositions suitable for the present invention are
the paste and gel formulations detailed under Tables III and
IV.
TABLE III ______________________________________ Bicarbonate Paste
Composition COMPONENT WT. % ______________________________________
Sorbitol 30.80 Syloid 63XX (abrasive silica) 20.00 Sodium
Bicarbonate 15.00 Sodium Carbonate 5.00 PEG 32 (polyethylene
glycol) 5.00 Sodium Pentaphosphate 4.00 Sodium Tetrapyrophosphate
3.00 Sodium Lauryl Sulfate 2.98 SD Alcohol 38B 2.85 Sylox 15x
(thickening silica) 2.00 Cellulose Gum 0.80 Sodium Saccharin 0.50
Sodium Fluoride 0.46 Titanium Dioxide 0.30 Deionized Water balance
______________________________________
TABLE IV ______________________________________ Peroxide Gel
Composition COMPONENT WT. % ______________________________________
Carbopol 940 (2% solution) 20.00 Glycerin 40.00 Hydrogen Peroxide
(35% food grade) 12.00 FD&C Blue 0.005 Sodium Hydroxide (50%
soln) adjusted to pH 7.0 Deionized Water Balance
______________________________________
EXAMPLE 3
This Example illustrates a still further paste and gel combination
for use in whitening teeth, the formulations being detailed under
Table V and VI.
TABLE V ______________________________________ Bicarbonate Paste
Composition INGREDIENT WT. % ______________________________________
Polyol II (sorbitol and other sugars) 33.90 Calcium Carbonate 27.00
Sodium Bicarbonate 20.00 PEG 32 (polyethylene glycol) 5.00 Sodium
Lauryl Sulfate 3.00 SD Alcohol 38B 3.00 Sodium Monofluorophosphate
2.10 Flavor 1.00 Cellulose Gum 0.80 Sodium Saccharin 0.50 Titanium
Dioxide 0.30 Deionized Water Balance
______________________________________
TABLE VI ______________________________________ Peroxide Gel
Composition COMPONENT WT. % ______________________________________
Pluronic F127 25.00 Glycerin 25.00 Hydrogen Peroxide (35% food
grade) 20.00 PEG 1450 10.00 Dipotassium Pyrophosphate 0.750
Disodium Pyrophosphate 0.750 FD&C Blue 0.005 Phosphoric Acid
(85% w/w) 0.10 Deionized Water Balance
______________________________________
EXAMPLE 4
This Example illustrates a paste and gel combination incorporating
urea peroxide for use in whitening teeth according to the method of
the present invention, the formulations being detailed under Tables
VI and VII.
TABLE VII ______________________________________ Bicarbonate Paste
Composition INGREDIENT WT. % ______________________________________
Sorbitol 15.00 Glycerin 15.00 Calcium Carbonate 15.00 Syloid 63XX
(abrasive silica) 15.00 Sodium Bicarbonate 15.00 PEG 32
(polyethylene glycol) 5.000 Sylox 15x (thickening silica) 3.60
Sodium Lauryl Sulfate 2.50 SD Alcohol 38B 2.50 Sodium
Hexametaphosphate 2.00 Flavor 1.00 Cellulose Gum 0.80 Sodium
Saccharin 0.50 Sodium Fluoride 0.46 Titanium Dioxide 0.30 Deionized
Water Balance ______________________________________
TABLE VIII ______________________________________ Peroxide Gel
Composition COMPONENT WT. % ______________________________________
Pluronic F127 25.000 Glycerin 35.000 Urea Peroxide 10.00
Tetrapotassium Pyrophosphate 4.00 FD&C Blue 0.005 Phosphoric
Acid (85% w/w) 0.10 Deionized Water Balance
______________________________________
EXAMPLE 5
The following Example illustrates the whitening effectiveness of a
hydrogen peroxide and sodium bicarbonate combination wherein each
of these active components have been stored separate just prior to
use. Ordinarily, the peroxide and bicarbonate are combined within
ten minutes, preferably five minutes but optimally within two
minutes of their mixing (onto the teeth).
The test utilized the paste and gel components whose formulations
are detailed under Tables IX and X.
TABLE IX ______________________________________ Bicarbonate Paste
Composition INGREDIENT WT. % ______________________________________
Polyol II (sorbitol and other sugars) 33.60 Syloid 63XX (abrasive
silica) 30.00 Sodium Bicarbonate 10.00 PEG 32 (polyethylene glycol)
5.00 Sylox 15x (thickening silica) 2.00 Flavor 1.00 Sodium Lauryl
Sulfate 2.98 SD Alcohol 38B 2.84 Cellulose Gum 0.80 Sodium
Saccharin 0.54 Menthol 0.50 Sodium Fluoride 0.44 Titanium Dioxide
0.30 Deionized Water Balance
______________________________________
TABLE X ______________________________________ Peroxide Gel
Composition COMPONENT WT. % ______________________________________
Glycerin 40.00 Pluronic F127 22.00 Hydrogen Peroxide (35% food
grade) 17.14 Zinc Citrate Trihydrate 4.00 FD&C Blue 0.005
Phosphoric Acid (85% w/w) 0.15 Deionized Water Balance
______________________________________
Evaluation of whitening involved placing a tooth into the sampled
composition for the equivalent of two minutes per day exposure
(i.e. one week is equivalent to 14 minutes exposure). Subsequently
the test tooth was evaluated for whiteness on a Macbeth
Colorimeter. A Delta L value was recorded representing the
difference between the calorimeter reading of the tooth baseline
versus the value after exposure to the sampled composition. Where
the gel composition was used as a test substrate, the concentration
of hydrogen peroxide delivered was maintained at 3.0% active
hydrogen peroxide.
TABLE XI ______________________________________ Equivalent Use Time
(in Months) 0 One Two Three Delta L Values
______________________________________ Bicarbonate Phase 0 1 3 4
Gel Phase 0 8 18 21 Gel/Bicarb. Phase Combination 0 20 29 30
______________________________________
Values in Table XI are recorded as Delta L values. The higher the
Delta L value the more effective the whitening. The results
indicate that combination of gel/bicarbonate phase provided a
substantially greater whitening effect than the additive results of
the gel and bicarbonate phases separately. For instance, at the
equivalent use time of one month, the additive of a bicarbonate and
gel phase provides a Delta L value of 9. By contrast, combination
treatment with gel/bicarbonate phase results in a whitening with
Delta L value of 20.
EXAMPLE 6
The following Example demonstrates the effect of pH on whitening
performance. Compositions employed for these experiments were
essentially identical to those described under Table IX and X of
Example 5. The only differences were that the level of hydrogen
peroxide was varied as well as pH (by addition of appropriate
amounts sodium hydroxide or sodium carbonate). Table XII records
the Delta L values for one month of brushing.
TABLE XII ______________________________________ HYDROGEN PEROXIDE
LEVEL (% DELIVERED) pH DELTA L VALUE
______________________________________ 0.75 7.9 13 1.5 8.2 19 0.75
9.5 24 1.5 9.5 26 1.5 10.5 32
______________________________________
From the results listed in Table XII, it is evident that for any
given level of peroxide, the higher the pH the greater the
whitening performance.
The foregoing description and Examples illustrate selected
embodiments of the present invention and in light thereof various
modifications will be suggested to one skilled in the art, all of
which are within the spirit and purview of this invention.
* * * * *